|Publication number||US6976396 B2|
|Application number||US 10/720,717|
|Publication date||Dec 20, 2005|
|Filing date||Nov 24, 2003|
|Priority date||Nov 24, 2003|
|Also published as||EP1687619A1, US20050109119, WO2005057204A1|
|Publication number||10720717, 720717, US 6976396 B2, US 6976396B2, US-B2-6976396, US6976396 B2, US6976396B2|
|Inventors||Richard D. Roe, Clifford F. Shaeffer|
|Original Assignee||The Boeing Company|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Non-Patent Citations (2), Referenced by (7), Classifications (11), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention is related to non-destructive inspection equipment, and more particularly, to a loading device that applies a normal load to a composite structure being non-destructively inspected.
2. Description of Related Art
Non-destructive inspection of structures involves examining a structure without harming the structure or requiring significant disassembly of the structure. Non-destructive inspection is advantageous for many applications in which a thorough inspection of the exterior and/or interior of a structure is required. For example, non-destructive inspection is commonly utilized in the aircraft industry to inspect aircraft structures for any type of internal or external damage to the structure.
Among the structures that are routinely non-destructively tested are composite structures. In this regard, composite structures are commonly used throughout industry because of their engineering qualities, design flexibility, and low weight. As such, it is frequently desirable to inspect composite structures to identify any flaws, such as cracks, voids, or porosity that could adversely affect the performance of the composite structure.
Various types of sensors may be utilized to perform non-destructive inspections. One or more sensors may move over the area of the structure to be examined, and receive data regarding the structure. For example, a pulse-echo, thru-transmission, or shear wave sensor may be utilized to obtain ultrasonic data, such as thickness gauging, detection of laminar defects and porosity, and/or detection of cracks in the structure. Resonance, pulse echo, or mechanical impedance sensors may be utilized to provide indications of voids or porosity, such as in adhesive bondlines of the structure. The data acquired by the sensors is typically processed by a processing element, and the processed data may be presented to a user via a display or stored for subsequent analysis.
Certain internal flaws are more readily detectable when the structure being inspected is loaded so that the internal flaws become more apparent to the non-destructive inspection instruments. These internal flaws may include weak bonds that will separate when loaded or may include incomplete bonds between layers that contact one another when experiencing no load but that also readily separate once loaded. An applied load can also be used to counteract a preload on the structure to improve the inspection of the structure.
Existing loading devices use various techniques to apply a load to a structure being inspected. One destructive method of applying a load is to adhesively bond a button or other feature to a surface of the structure and cutting a portion of the structure around the adhered button. An instrument pulls the button until the portion of the structure adhered to the button breaks away from the structure, such that the maximum load indicates the structural strength of the structure but leaves a hole in the structure that must be repaired.
One non-destructive method of applying a load uses electromechanical means to magnetically apply a load to a ferromagnetic layer or portion of a structure being inspected. Such methods are limited to structures that include ferromagnetic materials since a magnet is needed to engage the structure. Unfortunately, this method is generally unsuitable for composite structures since many composites do not comprise ferromagnetic materials. A further non-destructive method consists of applying a vacuum to a surface of the structure to measure surface deformation that indicates internal or external flaws. Such vacuum stress systems require a relatively large suction area, which may limit access to the surface of the structure requiring inspection. In addition, such vacuum stress systems are not able to create a suction on a surface that defines protrusions because such protrusions would compromise the seal of the suction.
Accordingly, a need exists for a loading device for conveniently applying a load to a surface of a composite structure for non-destructive inspection. A need also exists for a loading device that can apply a load to a surface of a structure that defines protrusions.
The invention addresses the above needs and achieves other advantages by providing a loading device for applying a load, such as a normal load, to a structure during a non-destructive inspection of the structure. The loading device comprises a load indicator to indicate the load applied to the structure and may further comprise a connector attached to the load indicator for connecting the load indicator to the surface of the structure being inspected. The loading device also comprises a support for supporting the load indicator and connector. The support contacts a surface of the structure proximate the area of the structure to be inspected. A load applicator in mechanical communication with the connector, the load indicator, and/or the structure applies the load to the structure. The load improves the results of the non-destructive inspection by accentuating some internal defects in the structure.
The loading device of further embodiments of the invention comprises a support defining at least three legs that contact the structure and a plate connecting the three legs to which the load indicator is attached. In addition, the legs may comprise protective ends for contacting the surface of the structure and may define adjustable lengths. The load applicator may comprise a turnbuckle that attaches the connector to the load indicator such that the load is created by rotating the turnbuckle. The connector may also define a threaded orifice for connecting to a surface of the structure or for threading onto a protrusion removably adhered to the surface of the structure.
A method of applying a load to a surface of a structure is also provided by the present invention. The support of the loading device is positioned on the surface of the structure such that the support contacts the surface. A connector is connected to the surface of the structure and attached to a load indicator. The load indicator is supported by the support and indicates the load as the distance between the connector and the load indicator is adjusted which applies the load to the surface of the structure. Once the load has been applied, the structure may then be inspected to reveal internal defects accentuated by the load.
The method may further comprise the step of rotating a turnbuckle to adjust the distance between the connector and the load indicator. The length of the legs of the support may be adjusted to properly contact the surface of the structure. The method may also comprise alternative steps for connecting the connector to the surface of the structure.
Accordingly, a loading device and method for conveniently applying a load, such as a normal load, to a structure undergoing a non-destructive inspection are provided. The load accentuates certain internal defects such as weak bonds or separated bonds so that the defects are more apparent to a technician performing the inspection. The loading device of the present invention may also be used on surfaces of structures that comprise protrusions or do not comprise protrusions.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
With reference to
The loading device 10 of
As shown in
Referring again to the particular load applicator 28 of the illustrated embodiment, the turnbuckle preferably defines a top threaded orifice 30 that is threaded either directly or indirectly to a load-sensing portion 32 of the load indicator 14. In the illustrated embodiment, a hook 34 is threaded into the top threaded orifice 30 of the turnbuckle and hooked onto a similar hook-shaped portion of the load-sensing portion 32. Further embodiments of the present invention comprise alternative means of joining the turnbuckle to the load-sensing portion 32.
The turnbuckle also defines a bottom threaded orifice 40 that is threaded either directly or indirectly to the connector 12. The connector 12 of
To apply a normal load in tension as illustrated in
The load indicator 14 of
The load indicator 14 of
The plate 20 of
The legs 18 of the support 16 shown in
The legs 18 of the illustrated support 16 also comprise protective feet 44 at the end of the legs that contact the structure 50. The protective feet 44 protect the surface 54 of the structure 50 from being damaged when the loading device 10 is positioned on the structure and when loads counteracting the load are exerted on the surface of the structure through the legs when the load is applied. The protective feet 44 are threaded or adhered to the ends of the legs 18 opposite the plate and are preferably an elastomeric material; however, further embodiments may comprise feet that comprise other relatively soft or padded materials such as polymers, to list a non-limiting example. Still further embodiments of the loading device that apply a compressive load on the surface of the structure may comprise feet that contact the structure to withstand the counteracting load in tension.
To apply the normal load with the loading device 10 of
The loading device of the present invention applies a load to a surface of a composite structure undergoing a non-destructive inspection to accentuate internal defects in the structure. The load may cause weak bonds that would normally be undetected to fail such that the inspection will detect the disbond, or it may reveal disbonds between composite plies that contact one another when experiencing no load but that also readily separate once loaded. The non-destructive inspection advantageously incorporates traditional pulse-echo or through transmission ultrasonic techniques to detect disbonds or defects in the area of the structure being inspected. Further non-destructive inspection techniques may also be used with the loading device of the present invention. The ultrasonic inspection device, or other non-destructive inspection device, preferably produces a signal that may be processed by a processing element to produce a visual display, such as a graphic or numeric illustration, that the technician performing the inspection can monitor for indications of a disbond or defect. The processed signal may also be recorded for subsequent analysis of the inspection results. Any detected disbonds or defects requiring remediation may be repaired, or if necessary, the structure may be replaced.
The loading device of the present invention may be conveniently assembled on a surface of a structure and is compatible with surfaces at various orientations or having various surface features. In addition, the loading device provides convenient access to the surface of the structure proximate the location where the load is applied so that the non-destructive inspection may be conveniently performed. Furthermore, the loading device may be used on surfaces with or without protrusions. Accordingly, the loading device provides a load that can be conveniently applied to a surface of a composite structure for non-destructive inspection purposes.
Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
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|International Classification||G01M99/00, G01N3/08, G01N29/22|
|Cooperative Classification||G01N2291/0231, G01N2291/0422, G01N29/227, G01N2291/02854, G01N3/08|
|European Classification||G01N29/22P, G01N3/08|
|Nov 24, 2003||AS||Assignment|
Owner name: BOEING COMPANY, THE, ILLINOIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ROE, RICHARD D.;SHAEFFER, CLIFFORD;REEL/FRAME:014746/0840
Effective date: 20031121
|Jun 22, 2009||FPAY||Fee payment|
Year of fee payment: 4
|Mar 14, 2013||FPAY||Fee payment|
Year of fee payment: 8